2 organisms are crossed with the following genotypes: AaBbCcdd x aaBbCcDda) What is the probability for a descendant to be homozygous recessive for all characteristics?b) What is the probability for a descendant to be homozygous dominant for all characteristics?

I believe that question b can be solved by noticing that the second parent does not have allele A which makes it impossible => P = 0. However for question a, I cannot deduct a similar answer because both parents have at least one recessive allele for each characteristic. Is it really necessary to create a Punnett square for this problem or is there an easier way to solve this?